Foldable mobile handsets equipped with a two-axis hinge such that a display case can be in the vertical direction or the horizontal direction with respect to an operation unit case, the style of the handset being changeable through this two-axis hinge, have been known from before. For example, such a device is disclosed in Japanese Patent No. 4216887.
In addition, Unexamined Japanese Patent Application KOKAI Publication No. 2005-143000 discloses a mobile device comprising a main body having an operation unit, a cover having a display, and a connecting unit with a built-in camera, with the main body and the cover connected by the connecting unit and the connecting unit rotating so that the main body and cover can slide relative to each other.
As can be seen in the example disclosed in Japanese Patent No. 4216887, with a conventional two-axis hinge there are no restrictions on the two axes, which open two cases vertically and horizontally, so the case can be opened in an arbitrary direction. However, when the user releases the case swiftly in the vertical or horizontal direction to change the style of the mobile handset, the case may rotate in an unintended direction, making it difficult to smoothly operate the two-axis hinge.
In addition, when taking video with a mobile phone, it is desirable from the perspective of visibility to take video while viewing the display screen horizontally the same as the configuration of a normal movie, but with the example disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2005-143000, the display is a vertical screen, so switching to a horizontal display on this vertical screen would make the display smaller.